基于强度折减法的港珠澳大桥沉管隧道干坞工程高边坡稳定性分析

在列举和分析比较当前岩土工程领域边坡稳定性分析的各种主要方法的基础上,概述了强度折减法的基本原理、主要特点和优势,并以港珠澳大桥沉管隧道干坞大型临时工程拟建场地的岩质高边坡为实例,应用强度折减法基于FLAC3D软件对该边坡的稳定性进行了计算和分析,确定了边界条件和强度参数,计算了该边坡的安全系数,结果表明自然工况下边坡处于稳定状态,底部开挖以后边坡趋于欠稳定状态,同时指出了边坡的关键变形部位,可为后续的设计和施工提供参考。     

芽孢杆菌 B1胞外活性物质对球形棕囊藻的溶藻特性研究

从珠海香洲码头赤潮海水中分离获得1株对球形棕囊藻有显著溶藻效果的芽孢杆菌B1,研究了B1对棕囊藻的溶藻作用方式,溶藻过程中藻细胞结构变化,并采用透析、乙醇沉淀、有机溶剂萃取、酸碱及热稳定性分析等方法探讨了溶藻活性物质的性质.结果表明,B1无菌滤液对棕囊藻有较强的溶藻效应,除藻率达94.9%,B1通过分泌活性物质间接对球形棕囊藻的生长产生抑制;藻培养液中加入B1无菌滤液16 h后,藻细胞发生团聚,细胞壁失去完整性,56 h后藻细胞破碎,胞内物质溶出;相对分子质量<3 500的分泌物是溶藻过程中起主要作用的活性物质,具有较强极性和热稳定性,在121℃加热20 min后,仍然有良好的溶藻能力,除藻率达92.6%,活性物质在pH 9.0左右溶藻能力较强,在乙醇中不发生沉淀反应,由此推测该活性物质为含有酸性或碱性基团的非生物活性分子,不属于蛋白质、核酸、多糖等物质.     

Determination of alkali-labile phosphoprotein phosphorus from fish plasma using the Tb^3＋-tiron complex as a fluorescence probe

A sensitive method based on the fluorescence quenching effect of the Tb^3＋-Tiron complex is proposed for the determination of alkali-labile phosphoprotein phosphorus （ALP） released from fish plasma. The detection limit was 5.4 ng/ml （S/N=2）, and the relative standard deviation of the quenching effect （6 replicates） was 4.6%. The results obtained by the proposed method were in good agreement with those obtained by the colorimetric assay. The advantages of the present method are its relatively simple detection procedure, the lack of toxic organic solvents, and high sensitivity.     

应用分子生物学与同位素示踪技术研究厌氧氨氧化菌活性及功效

厌氧氨氧化是一个新发现的氮循环途径,与反硝化作用都产生氮气,但准确衡量厌氧氨氧化活性及功效的相关方法还是个难题.本研究联合应用分子生物学与同位索示踪技术,以北京某污水处理厂的活性污泥为实验样品,研究其中厌氧氨氧化菌的存在、活性和功效.厌氧氨氧化菌的分子生物学分析是通过16S rRNA进行,选择两步引物分别为pla46-...     

温室条件下UV-B辐射对蓝藻结皮生长和超微结构的影响

UV-B辐射是野外蓝藻结皮经常面临的一种环境胁迫因子.报道了温室条件下UV-B辐射对蓝藻结皮形态、生理和超微结构特征的影响.在本研究中,首先通过接种具鞘微鞘藻和爪哇伪枝藻形成初始蓝藻结皮,接着以初始蓝藻结皮为材料进行3种辐射处理:光合有效辐射、UV-B辐射+光合有效辐射和N-乙酰半胱氨酸+UV-B辐射+光合有效辐射.在...     

荞麦皮生物吸附去除水中罗丹明B的吸附条件响应面法及热力学研究

采用Box-Behnken响应面优化实验设计对荞麦皮生物吸附去除水中染料罗丹明B的影响因素（如温度、pH值、染料初始浓度、吸附剂用量）进行研究,建立了去除率与上述因素之间的二次多项式模型,得到荞麦皮去除罗丹明B的最佳条件为：温度50℃、pH=2、罗丹明B初始浓度100mg·L^-1、吸附剂用量11.75g·L^-1,最...     

Effects of Cu（Ⅱ） and humic acid on atrazine photodegradation

This work was designed to explore the characteristics of photodegradation of herbicides in the copper-polluted water body. The results showed that Cu(II) alone could induce a photo Fenton-like reaction to enhance the degradation of atrazine, in which hydroxyl radical ( OH) was a main active species. Humic acids restrained atrazine degradation, nevertheless, when introducing Cu(II), the photodegradation was accelerated, in which singlet oxygen (1O2) replaced OH acting as the prevailing species. A feasible mechanism for the photochemical process was also proposed, which is helpful for better understanding the environmental photochemistry of atrazine in the copper-polluted water.     

Antimicrobial activity of thin metallic silver flakes, waste products of a manufacturing process

The aim of the research was to develop new products and processes from a manufacturing waste from an Italian metallurgic company. The company produced thin silver metallic films and the production scraps were silver flakes. The possibility to use the silver flakes in water disinfection processes was studied. The antimicrobial activity of the flakes was investigated in batch using Escherichia coli as Gram-negative microorganism model. The flakes did not show any antimicrobial activity, so they were activated with two different processes: thermal activation in reducing atmosphere and chemical activation, obtaining, respectively, reduced flakes (RF) and chemical flakes (CF). The flakes, activated with either treatment, showed antimicrobial activity against E. coli. The kill rate was dependent on the type of activated flakes. The chemical flakes were more efficient than reduced flakes. The kill rate determined for 1 g of CF, 1.0 ± 0.2 min⁻¹, was greater than the kill rate determined for 1 g of RF, 0.069 ± 0.004 min⁻¹. This was confirmed also by the minimum inhibitory concentration values. It was demonstrated that the antimicrobial capability was dependent on flakes amount and on the type of aqueous medium. Furthermore, the flakes maintained their properties also when used a second time. Finally, the antimicrobial activities of flakes were tested in an effluent of a wastewater treatment plant where a variety of heterotrophic bacteria were present.     

Arbuscular mycorrhizal fungi alter the response of growth and nutrient uptake of snap bean（Phaseolus vulgaris L.） to O_3

The effects of arbuscular mycorrhizal fungi (AMF) Glomus mosseae on the responses to elevated O3 in growth and nutrition of snap bean (Phaseolus vulgaris L. cv Guangzhouyuan) were investigated. Exposure was conducted in growth chambers by using three O3 concentrations (20 (CF), 80 (CFO1) and 120 nL/L (CFO2); 8 hr/day for 75 days). Results showed that elevated O3 slightly impacted overall mycorrhizal colonization, but significantly decreased the proportional frequency of hypha and increased the proportional frequency of spores and vesicles, suggesting that O3 had significant effects on mycorrhizal structure. Elevated O3 significantly decreased yield, dry mass and nutrient contents (N, P, K, Ca and Mg) in both non-mycorrhizal and mycorrhizal plants. However, significant interactive effects were found in most variables due to that the reduction by O3 in the mycorrhizal plants was less than that in the non-mycorrhizal plants. Additionally, AMF increased the concentrations of N, P, Ca, and Mg in shoot and root. It can be concluded that AMF alleviated detrimental effects of increasing O3 on host plant through improving plant nutrition and growth.     

Visible light responsive N-F-codoped TiO2 photocatalysts for the degradation of 4-chlorophenol

Visible light responsive N-F-codoped TiO₂ photocatalysts exhibit a higher catalytic activity than N-doped TiO₂ for the degradation of 4-chlorophenol due to the synergistic effect of nonmetal elements.